The invention relates in an aspect to a method for determining the metabolic capacity of at least one enzyme and the use of various 13C-labeled substrates in such a method, respectively.
Enzymes significantly contribute to the degradation of harmful substances in the body of animals and humans. There is a multitude of various enzymes, e.g. cytochromes, which catalytically convert substrates.
As the enzymes or enzyme systems (in what follows reference will always only be made to enzymes while both will be meant) exert important functions, it is of high importance to determine their functional capacity in an organism. This happens nowadays e.g. via examinations directly on the cell cultures outside of the organism, which has the disadvantage that the enzyme is not examined in its native environment. Examinations in the organism typically involve the administration of isotope-labeled substrates, which are metabolized by the enzyme. The administration or application takes place either by surgical interventions, such as e.g. the direct injection into the heart, or else by other methods, such as e.g. taking the substrate orally.
The non-surgical applications here almost always have the disadvantage that the availability of the substrate in the blood takes several minutes. That is to say, the time period at the start of which the concentration of the substrate S in the blood increases until it has taken on a maximum concentration (without taking into account possible decreases in concentration by metabolism) takes several minutes.
An alternative is the high-sensitive detection of trace gases without prior administration of a substrate. But that has the disadvantage that the exact anamnesis of the examined individual and all the causes for the enrichment of a gas in the breathing air must be known. As a matter of principle, however, this anamnesis cannot be determined accurately enough.